But, in a tantalizing concession that he hasn't totally closed the door on another comeback, Phelps told The Associated Press that it might be tough to stay away from the pool — especially if he attends the upcoming world championships in Budapest.

"The true test will be, if I do end up going over to the worlds this summer, do I have that itch again?" Phelps said Tuesday during a telephone interview.

He was already strongly considering his first comeback when he attended the 2013 championships in Barcelona, and there was no doubt he'd be back for his fifth Olympics when that meet ended.

"I was just like, 'This is a joke. How can these guys be swimming this slow?'" recalled Phelps, who was especially motivated by a disappointing performance from the men's relay team. "We'll see if I get that itch again."

For now, he's happy with his post-swimming life, which includes a new sponsorship deal with Colgate in which he is pushing water conservation.

"He has started standing by himself a little bit from time to time," Phelps said. "He's on the move all the time now and loving it. He's killing it. It's so fun to watch him. Every day, it's something different, something special. It's a treat for me to see it face to face. It's wild. It's mind-blowing for Nicole and I. We still look at each other sometimes and go, 'Wow, we have a son. This is our son.'"

If Phelps returns to competitive swimming, the demands of training would surely cut heavily into his family time. That's why, if he tries to predict what the future might hold, it doesn't include a sixth Olympics at Tokyo in 2020.

"I'm having so many amazing experience, so many cool experiences, with my family," he said. "I don't see myself making a comeback. I have no desire right now to do it. I'm in the second chapter of my life. I have a lot of things I now want to accomplish. I'm realizing that more and more. This is a really cool opportunity for me to do some things I was not able to do when I was swimming."

That includes lending his still-considerable clout to issues that he considers important to swimming and the world.

In the lead-up to the Rio Games, Phelps talked for the first time about the scourge of doping, saying he wasn't sure if he had ever competed in a totally clean race, even while winning a record 23 gold medals and 28 medals in all.

In February, he took it a step further by testifying at a congressional hearing on improving anti-doping measures. He said athletes don't believe in the testing programs that are already in place, and he urged lawmakers to help "ensure the system is fair and reliable."

"Throughout my career, I never spoke out about anything," Phelps conceded. "I stayed in my lane and focused on what I was doing. To get out front and speak out on things that are passionate to me, to take different approaches to things I want to talk about in different walks of life, that's pretty cool and pretty special for me. The opportunities I have are absolutely amazing.

"Hopefully," he added, "I can change some things and make a difference."

He's doing a media blitz this week for his new deal with Colgate and the "Save Water" program, coinciding with Earth Day on Saturday.

"It completely blows my mind to think about how much you can waste when you brush your teeth twice a day," Phelps said. "If you leave the water running while you brush your teeth, it's wasting four to five gallons every time you do that. Every time. If we can get people to stop doing that, think how many millions of people in the world could contribute in just that small way."

Phelps said this second retirement, coming after an Olympics in which he won five gold medals and a silver with his new family along for the ride, has enabled him to truly appreciate the enormous accomplishments of his career.